Frequency-changer.



No. 872,535. I PATENTED DEC. 3, 1907. J. E. NOBGGBRATH.

FREQUENCY CHANGER.

AP PLIOATIOR FILED D1104, 1905.

Witnesses: Inventor:

W/aajq/ Jakob E. Noegeroigh.

UNITED STATES PATENT OFFICE.

JAKOB E. NOEGGERATH, OF SCHENECTADY, NEW YORK, ASSIGNQR TO GENERAL ELECTRIC COMPANY, A-CORPORATION OF NEW YORK.

FIRE QUINCY-CHANGER.

To all whom it may concern:

Be it known that I, JAKOB E. Nonsen- BATH, a citizen of the United States, residing at Schenectady, county of Schenectady,

5 State of New York, have invented certain new and useful Improvements in Frequency Changers, of which the following is a specification.

My invention relates to frequency-changers for alternating-current circuits, and its object is to provide a frequenc'y-chan er which is in many cases of more economica construction than those employed heretofore, and, which possesses the characteristic of automatically compounding, for maintaining unity powerfactor, or for varying with increasi load the ratio of the electromotive force delivered to that supplied.

Frequency-changers have been built heretofore, consisting of a synchronous motor supplied with alternating-current from one circuit, and an alternating-current enerator mechanically connected thereto an supplying current of a different frequency to' aseo- 0nd circuit.

My invention in its broadest aspects consists in substituting rotary converters for the motor and generator heretofore employed. By the term rotary converter is understood in the art, the type ofomachine having a diroot-current field excitation and an armature,

provided with a closed windin connected 0th to a commutator and to co ector rings. In such a machine, if alternating-current is supplied to the collector rings, direct-current may be taken from the commutator, and vice versa.

My invention consists supplying alternating-current to one converter, supplying direct-current from that converterto the second, and supplying alternating-current from the second converter to the second alternating-current circuit. Such an arrangement is cheaper to construct than the ordinary motor generator set, both because the rotary converters are self-exciting, and so require no separate exciter, and also because the armature reaction is less than in motor or generator, so that less field copper is required, and the alternating and direct-currents in the armature combine in such a manner that armature heating is less than in a motor or gen 5 verter to the other may be approximately Specification of Letters Patent.

Appli ati and December 4. 1905-. Serial No. 290.089.

.conductors 1, 2, 3.

PatentedDec. 3, 1907.

proportional to the load, this current may be employed, by inserting field coils in the direct-current connections between the two machines, so as automatically to compound the frequency-changer so as to make itoperate at unity power-factor for varying loads,

V or, if desired, it may be made to increase automatically the voltage delivered in ro ortion to the impressed voltage as the oa increases.

It is well understood in the art that an inverted rotary converter,that is, a converter receiving direct-current and delivering alternating-current, if suppl ing a circuit in which the frequency is not ed, is likely to run up to excessive s eeds if a heavy lagging current is taken by t 1e load on the alternating-current circuit supplied, and even if the load does not vary so as to produce an excessive speed, the frequency of the supplied cir- 76 cuit varies with the variation of load. Consequently, if constant frequency in the load circuit is required, it is essential so to arrange the second converter that its speed will remain constant. This is most readily accom- 8O plished by mounting the two machines on the same shaft. When this is done the contator and collector rings in the usual manner,

and the collector rings are connected to the alternating-current circuit indicated by the' The field of the conrovided with shunt field coils a verter A is and series eld coils a which are supplied with direct-current from thecommutator. The rotary converter B has its collector rings connected to a second alternating-current circuit indicated by the conductors 4, 5, 6 and on the direct-current side is connected to the commutator of converter A. Converter B is provided with shunt field coils b and series coils b. The ratio of the pole 110 half cycles will be supplied by the converter.

B to the load'circuit 4, 5, 6.

It will be seen that the connections between the direct current sides of the two converters include the field coils a of the converter A and field coils b to converter B. In this manner either or-both machines may be compounded. By properly adjusting the compounding of the converter A,lthe powerfactor of the alternating-current taken from the supply circuit 1-, 2, 3 may be controlled, and if inductances, as indicated at D be included in the circuit 1, 2, 3, the seriescoil. a may be. adjusted so as to increase the voltage on the direct-current side relatively to the voltage on the alternating-current side with increasing load. In this way the alternating-current voltage. delivered to the alternating circuit 4, 5, 6 may be made 'to'inc'rease" as the load increases,or in other-words, the

frequency-changer may be compounded. If I 2, 3 isitself sufiiciently inductive, the inductances D r'nayofcourse be} tary-converters, one supplied with alternatthe circuit 1,

omitted;

Since the two converters are connected 5 both mechanically and electrically, energy 1 may be delivered by one to the other in either root-current sides of said. converters whereby form, and the proportions of the amounts of energy delivered electrically and mechanically will depend for any given load on the relative voltagesinduced at the commuta tors of the twomachines. For most efficient operation it is desirable that the transference of energy from one circuit to' the other should be almost wholly electrical for all loads; but since the voltage at the commutai tor of converter A is increased with increas-- ing load by theseries coils-a it is desirable that the induced voltage inconverter B should also increase. For this reason Ihave shown the series coils I) applied tothe con verter B and inserted in serles with the coils a in the connections betweenthe direct-cur rent sides of the two converters.

The frequency-changer, as described above, is self-exciting, and consequently does not require a separate exciter as does the usual alternating. current motor-generator set. Furthermore, as has been heretofore ointed out, the amount of co per required 0th in field and armature is ess than in a motorgenerator set, so that in many cases the cost of the frequency-changer as a whole is less. Furthermore, automatic compounding is obtained in a simple manner with a frequencychan'ger arranged in accordance with my invention. I o

As has been pointed out above, the two converterszare preferably so ad'usted that almostall the energy transferred etween them is transferred electrically. Consequently the mechanical connection between the twoconverters serves for the most art simply to maintain the second inverte( rotary at the proper speed. Consequently it is'not absolutely essential .to m invention in its broadest aspect that t e two converters sh ould be mechanically coupled. The mechanical connection between the two may be omitted, ifother synchronous machines are connected to the circuit 4-, ,5, 6, or if the speed of the inverted rotary is maintained constant by any automatic means, such, for instance,

as is shown in Patent No. 712,561, issuedto A. D. Lunt,'November 4,1902.

What I claim as new and desire-to secure by Letters Patent of the United States, is,

1. In combination, two alternating-current circuits of different frequencies, two rotary-"converters, one supplled with'alternatmi-current from one of said circuits and the ot er supplying alternatln -current to the second circuit, and electrica connections betweenthe direct-current sides of said converters whereby one supplies direct-current to the other.

' .2; In combination, two alternating-currentcircuits of different frequencies, two roinglecurrent. from one of said circuits and the ot er. supplying alternating-current .to the secondcircuit, connections between the dione supfplies direct-current to the other, and

means or varyingthe field-strength of one or both convertersupon variation in the amount of said .directcurrent'. I

3: In combination, two alternating current circuits .ofdifferent frequencies, two rotary-converters, one supplied with alternating-current from one of said circuits and the other supplying alternating-current to the second c1rcuit,.connections between the direct-current sides of said converters whereby one supplies direct-current to the other, and field coils included in said connections.

4. In combination, two alternating-current circuits of different frequencies, two rotary converters mechanically connected, one supplied with alternatiiig-current from one of said circuits'and the other supplying alternatin'g-current to the second circuit, and connections between the direct-current sides of said converters wherebyf one supplies direct current to the other.

5. In combination, two alternating-current circuits of diiierent frequencies, two rotary converters mechanically connected, one supplied with alternating-current from one of said circuits and the other supplying alternatur -current to the second circuit, connections between the direct-current sides of said. converters whereby one supplies direct-current to the other, and vfield coils included in said'connections.

6. In comblnation, two alternating-current circuits, two rotary converters of difi'erent numoers of mounted on t e same shait, one of, said converters being supplied with alternating-current from one of said circuits and'the other supplying alternating-current of a diflerent frequency to the other circuit, and connec tions between the direct-current sides of said converters whereby one supplies direct-cur- 1,0 rent to the other.

7. In combination, two alternating-current circuits, two'rotaxy converters of different numbers of oles ha their armatures mounted'on t e same sh t, one of said converters being su plied with alternating-current from one 0 said circuits'and the other supplying alternatin -current ofa different frequency to the other circuit, connections between the direct-current sides of said converters whereby one supplies direct-current to the other, and field coils included in Said connections.

8, lncombination, an alternating-currents conv rter:

in. r

load circuit supplied from the other conmeans for automatically increasage impressed by the second conhe load circuit with. increasing ploles havin 7 their armatures' current of a different and a load circuit supplied from the other in combination, two rotary converters of (l'iierentpole numbers mechanically and electrically connected, a source of currentconnected to and supplying one converter, a

circuit, a rotary converter suppliedntherefrom, inductances-inserted in the connections between said circuit and'said converter,

means for varying the field strength of said converter with'vaging 1oad,- e d on,

verter suppliedwi direct-current from the first converter, and a; load circuit supplied from the second converter with'alternatingfrequency from that of the su ply circuit.

n combination, an alternating-current.

circuit, a rotary converter supplied there-'- from and having a series field winding, inductances' inserted in the*connect1ons-between said circuit and said converter, a sechaving its armature on the same shaft with the first and sup lied with direct-current therefrom, and a oad circuit supplied with alternating-current from the second converter; 1 v

13. A frequency-ch er consisting of two rotary converters of d erent pole numbers havin their armatures mechanically -connecte( I 15L A frequency-chap er consisting of two rotary converters of d erent pole numbers havin' their armatures mechanically con-- necte andelectrlcal connections between the direct-current sides of said converters" whereby one supplies direct-current to the other.

' 0nd converter of a different number of poles v Y 1.5, A frequencymhanger consisting'of two I rotary converters of. difierent pole numbers havin their armatures mechanically connecte ,electrical connections between the direct-current sides of said converters whereby one sup lies direct-current to the other, and field coils included in said connections.

In witness whereof, I have hereunto set w my hand this 29th day of November, 1905',

JAKOB E. NOEGGERATH.

Witnesses:

BENJAMIN B. HULL, HELEN ORFoRn 

